Arthropod-borne pathogens account for millions of death each year. Understanding the genetic basis of vector susceptibility to pathogens is pivotal to novel disease control strategies. The hypothesis that induction of apoptosis is a fundamental innate immune response has been supported by virology studies, which demonstrated that the anti- apoptotic activities of many viral genes are essential for their infectivity and/or virulence. However, the cellular mechanism mediating the induction of apoptosis following virus infection remained enigmatic. In addition, studies with cultured insect cells showed that either there is a lack of apoptosis, or the pro-apoptotic response happens relatively late, casting doubt on the functional significance of apoptosis as an innate immunity. Using in vivo mosquito models mimicking native routes of viral infection, we found that there is a rapid induction of pro-apoptotic genes (RIPAG) within a few hours following exposure to DNA/RNA viruses. More importantly, using genetic tools in Drosophila, we showed that the RIPAG, and the ensuing apoptosis, is responsible for denying the expression of viral genes and blocking/limiting the infection. Animals with compromised RIAPG are much more susceptible to viral infection than wild type. In this proposal, we seek to unravel the transcriptional mechanisms and the regulatory pathway(s) controlling RIPAG using a combination of Drosophila genetics and comparative genomics. In addition, utilizing the information obtained through the mechanistic analysis, we will test the hypothesis that increased innate immunity against viral infection may be achieved by enhancing the RIPAG response to viral infection. Finally, we assess the fitness of the antiviral constructs we create in Drosophila, then translate the most powerful and most fit constructs to two mosquito vectors and perform preliminary evaluations of transgene effectiveness against Dengue.